1. Field of the Invention
The invention relates in general to compounds and electronic devices comprising metallic complexes, and more particularly, to compounds comprising Group 8-10 metallic complexes and their use as active layers within electronic devices, as indicators, and as catalysts.
2. Background
Organic electronic devices that emit light, such as light-emitting diodes as used in displays, are present in many different kinds of electronic equipment. In many of these devices, an organic active layer is sandwiched between two electrical contact layers. At least one of the electrical contact layers is light transmitting so that light can pass through the electrical contact layer. The organic active layer emits light through the light-transmitting electrical contact layer upon application of a voltage across the electrical contact layers.
Organic electroluminescent compounds used as the active component in organic light-emitting diodes (“OLEDs”) are well known. Simple organic molecules, such as anthracene, thiadiazole derivatives, and coumarin derivatives are known to be electroluminescent. Semiconductive conjugated polymers have also been used as electroluminescent components. Complexes of 8-hydroxyquinolate with trivalent metal ions, particularly aluminum, have been extensively used as electroluminescent components.
Phosphorescent metal complexes, such as fac-tris(2-phenylpyridine) iridium can be used as the active component in OLEDs. A conventional belief is that in order to achieve efficient devices with phosphorescent metal complex emitters, the emitter must be doped in a charge-transporting host material. In one specific conventional OLED, the active layer can be poly(N-vinyl carbazole) doped with fac-tris[2-(4′,5′-difluorophenyl)pyridine-C′2,N]iridium(III). Other electroluminescent devices with an active layer of polymer doped with organometallic complexes of iridium or platinum have been disclosed. However, most of these complexes have emission spectra with peaks in the green or green-blue region. A continuing need exists for electroluminescent compounds having an emission maximum closer to the blue region of the visible light spectrum.